A circular stapler is one device that can be used in surgical applications for the joining of body tissue. In the area of surgical anastomotic stapling, it can be used for joining pieces of tissue in a manner such that a continuous pathway, lumen, or surgical opening, is formed after the tissue is stapled together. This lumen is formed when a circle of staples is used to join two pieces of tissue after which the tissue interior to the innermost circle of staples is cut out by a concentric circular retractable blade. Retraction of the circular stapler removes the cut tissue to form a lumen. An example of a circular stapler is given in U.S. Pat. No. 5,104,025 to Main et al. Other devices and methods can also be used to produce anastomoses.
When used in surgery for colorectal disorders the circular stapler is used to reform the colon into a continuous lumen after a section is removed for treatment of the disease state. Concerns about leakage of the colon contents into the peritoneal cavity from the anastomosis site are prevalent during this type of surgery. A complete seal between the pieces of tissue that are joined is desirable to prevent leakage. Another concern in colon resections is reduction of the lumen diameter after surgery. This reduction in diameter would result in the restriction of the passage of biological material.
Using a stapler that forms a lumen with a diameter close to that of the preoperative healthy colon is desirable to prevent these flow restrictions. Typically the circle of staples formed is between 2-4 cm in diameter and is made from 20 to 40 small, metallic staples. Due in part to the presence of these metallic staples, another concern in tissue resection is tearing of the tissue at the anastomosis site.
Modifications to circular staplers as well as the development of other devices have been described to address the concerns that may occur during stapling of body tissue and the formation of a tissue anastomosis. A device used to create an anastomosis without staples is described in U.S. Pat. Nos. 5,222,963 to Brinkerhoff et al. and 5,250,058 to Miller et al. This device uses a tissue coupler made from a bioabsorbable polymer. A concern in using this device is the risk of tissue separation at the anastomosis site after the polymer has been absorbed by the body. A similar concern is shared for the device described in U.S. Pat. No. 5,346,501 to Regula et al., as it also uses only a bioabsorbable material for the formation of the anastomosis.
To alleviate the concern about tissue separation after the absorption of a bioabsorbable material, non-absorbable biocompatible metal staples can be used to form the anastomosis. However, leakage and/or tearing at the site where the tissue is joined are concerns when only metal staples are used. In order to prevent leakage and/or tearing, supporting buttresses constructed of both non-bioabsorbable and bioabsorbable materials for use with surgical staplers have been described in various publications. U.S. Pat. No. 6,503,257 to Grant et al. teaches a method for using an adhesive to releasably attach a buttress construct to a surgical stapling instrument. This buttress addresses both the leakage and/or tearing concerns that occur during tissue stapling. The use of metal staples provides for the long-term joining of the tissue. However, the buttress must be carefully aligned onto the stapling instrument and a suitable adhesive must be used on the surfaces of both the buttress and the stapling instrument to secure the buttress to the stapling instrument. Further, withdrawing the anvil part of the stapler through the buttress may be difficult, as the inner diameter of the buttress is smaller than the outer diameter of the stapler anvil.
A potential concern about use of an adhesive substance applied to the buttress is incompatibility of the adhesive with the tissue in the patient that it contacts. One mode of this tissue contact may be between the adhesive-containing surface of the buttress and tissue of the patient in the area of the anastomotic junction. The adhesive may also be transferred onto the staple surfaces as they penetrate through the adhesive present on the buttress and may then be carried into the tissue of the patient. An alternative to using adhesive on the buttress would be to design the buttress with protrusions that extend from the perimeter of the buttress and which may be provided with adhesive. These protrusions could be used to securely fasten the buttress to the circular stapler body and to the circular stapler anvil. Further, these protrusions could be disruptably attached, connected or fastened to the buttress to allow the protrusions to separate from the buttress in a controlled fashion.